- Phase I (closed to accrual as of 7/9/03): Patients receive oral imatinib mesylate once daily beginning on day 1 and interferon alfa (IFN-A) subcutaneously once daily or 3 times weekly beginning on day 14. Courses repeat every 35 days for up to 1 year in the absence of disease progression or unacceptable toxicity. After completion of 1 year of therapy, patients may receive additional therapy, provided that the patient is benefiting from imatinib mesylate. IFN-A is discontinued in patients who achieve a molecular remission that is confirmed on 2 successive bone marrow samples. Imatinib mesylate is discontinued in patients who achieve and maintain a molecular remission for 2 years.